A pure electric engineering machinery cooling and heating air conditioning system and control method thereof

Abstract

The present invention discloses a pure electric engineering machinery cooling and heating air conditioning system and a control method thereof, the system comprises a compressor, a first plate heat exchanger, an electronic expansion valve, a condenser, a thermal expansion valve, and a second plate heat exchanger which are sequentially connected to form a refrigerant circulation loop; the system also comprises a cab water air conditioning core, the liquid outlet of the cab water air conditioning core is respectively connected to the liquid inlet of the first plate heat exchanger and the second plate heat exchanger, the liquid inlet of the cab water air conditioning core is connected to a water pump, the water pump is respectively connected to the liquid outlet of the first plate heat exchanger through a first stop valve, and is connected to the liquid outlet of the second plate heat exchanger through a second stop valve. The system has a simple layout, low cost, and easy control.

Description

Technical Field

[0001] The invention relates to a pure electric engineering machinery cooling and heating air conditioning system and a control method thereof, belonging to the technical field of electric vehicles. Background Art

[0002] A pure electric vehicle is a vehicle that uses an onboard power source as its motive force, uses an electric motor to drive the wheels, and uses the electric motor as its motive force to drive the hydraulic system to do work. There are currently two solutions for controlling the temperature of the cab: First, an air conditioning system is used for cooling, and a PTC heating system is used for heating. These are two independent systems. The refrigerant circuit of the air conditioning system only cools the cab, and the PTC heating system only heats the cab. The dual system has high costs and complex layouts, and has low energy efficiency when heating, which greatly affects the vehicle's range. Second, a heat pump system is used. The heat pump system achieves the interchange of the condenser and the evaporator through the reversal of the four-way valve, thereby achieving the cooling and heating needs of the cab. This system is greatly affected by the ambient temperature when heating in winter, and has a low heating efficiency in low temperature environments, or it cannot heat. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a heating and cooling air conditioning system and a control method thereof which can effectively control the temperature of a cab of a pure electric engineering machinery and has a simple layout and saves costs.

[0004] In order to solve the above technical problems, the present invention first discloses a pure electric engineering machinery heating and cooling air-conditioning system, which includes a compressor, a first plate heat exchanger, an electronic expansion valve, a condenser, a thermal expansion valve and a second plate heat exchanger which are connected in sequence to form a refrigerant circulation loop; the system also includes a cab water air-conditioning core, the liquid outlet of the cab water air-conditioning core is respectively connected to the liquid inlet of the first plate heat exchanger and the second plate heat exchanger, the liquid inlet of the cab water air-conditioning core is connected to a water pump, and the water pump is respectively connected to the liquid outlet of the first plate heat exchanger through a first stop valve, and is connected to the liquid outlet of the second plate heat exchanger through a second stop valve.

[0005] Furthermore, the first plate heat exchanger and the second plate heat exchanger both include an antifreeze layer and a refrigerant layer.

[0006] Furthermore, the second plate heat exchanger is also connected to the hydraulic system and the proportional valve in sequence to form a loop.

[0007] Furthermore, the second plate heat exchanger includes an antifreeze layer, a refrigerant layer and a hydraulic oil layer in sequence, that is, the second plate heat exchanger is a plate heat exchanger with three branches and three media coexisting, and forms a hydraulic oil circulation loop with the hydraulic system and the proportional valve.

[0008] Each component of the present invention is controlled by a controller, and the controller can realize the conversion of cooling and heating, as well as the recovery of waste heat in the system by controlling the valve components. This includes controlling the circulation of hydraulic oil by controlling the proportional valve, realizing waste heat recovery when it is opened proportionally, and not recovering waste heat when it is completely closed; controlling the circulation of two antifreeze liquids by controlling the on-off of the first and second stop valves to realize the switching of cooling and heating of the cab; realizing the function of the first plate heat exchanger in the refrigerant circuit by controlling the full opening of the electronic expansion valve, which is a channel when fully opened, and the entire refrigerant cycle is a refrigeration cycle. The refrigerant condenses at the condenser and evaporates at the second plate heat exchanger. The refrigerant and antifreeze liquid exchange heat to provide cooling for the cab refrigeration; according to the condenser When the evaporation temperature of the internal refrigerant is adjusted, the first plate heat exchanger is a condenser, and the low-temperature antifreeze and the high-temperature refrigerant exchange heat. The antifreeze is heated up, and the refrigerant is cooled and condensed. The condenser and the second plate heat exchanger in the refrigerant cycle are evaporators. The refrigerant exchanges heat with the ambient temperature at the condenser and exchanges heat with the hydraulic oil at the second plate heat exchanger. The ambient temperature and the high-temperature hydraulic oil provide heat sources for the evaporation of the refrigerant. At the same time, the ambient temperature and the hydraulic oil are further cooled) to respectively realize the recovery of waste heat from the hydraulic oil, the secondary evaporation of the refrigerant, and the refrigeration of the cab water air conditioning circulation loop.

[0009] The present invention also discloses a control method for the above-mentioned pure electric engineering machinery cooling and heating air conditioning system, which includes cooling control and heating control.

[0010] Refrigeration control: The controller controls the electronic expansion valve to be fully open, and the thermal expansion valve adjusts the opening according to the evaporation temperature of the second plate heat exchanger. At this time, the first plate heat exchanger is only a channel. The high-temperature and high-pressure gaseous refrigerant compressed by the compressor passes through the first plate heat exchanger and the electronic expansion valve in turn to the condenser, condenses through the condenser, and then passes through the thermal expansion valve to the second plate heat exchanger for evaporation, and then returns to the compressor to form a refrigerant cycle; at the same time, the controller controls the first stop valve to be closed and the second stop valve to be opened. The antifreeze that has absorbed the heat from the cab environment and heated up circulates to the second plate heat exchanger to exchange heat with the refrigerant for cooling, and then passes through the second stop valve and the water pump in turn to circulate to the cab water air conditioning core to cool the cab. In the above process, the antifreeze absorbs heat from the environment in the cab, and the liquid refrigerant in the second plate heat exchanger exchanges heat with the antifreeze, the refrigerant absorbs heat and evaporates, and the antifreeze is cooled. During the cooling process, the controller adjusts the working status of the compressor, the condenser fan and the water pump of the condenser according to the instructions of the air conditioner regulator in the cab and the detected inlet liquid (antifreeze) temperature of the second plate heat exchanger and the high and low pressure values ​​in the refrigerant circuit;

[0011] Heating control: The controller controls the opening of the electronic expansion valve according to the evaporation temperature of the refrigerant in the condenser, and the thermal expansion valve adjusts the opening according to the evaporation temperature of the refrigerant in the second plate heat exchanger. The high-temperature and high-pressure gaseous refrigerant compressed by the compressor condenses in the first plate heat exchanger and reaches the condenser through the electronic expansion valve. At this time, the condenser acts as an evaporator to evaporate the refrigerant once (the evaporation is incomplete when the ambient temperature is low), and then reaches the second plate heat exchanger through the thermal expansion valve. The second plate heat exchanger evaporates the refrigerant for the second time and then returns to the compressor to form a refrigerant cycle; at the same time, the controller controls the first stop valve to open and the second stop valve to close, and the antifreeze after the cab releases heat and cools circulates to the first plate heat exchanger to absorb heat and heat up. The heated antifreeze then passes through the first stop valve and the water pump in turn to circulate to the cab water air conditioning core to heat the cab. In the above process, the gaseous refrigerant in the first plate heat exchanger exchanges heat with the antifreeze, the refrigerant cools down and condenses, and the antifreeze absorbs heat and heats up.

[0012] Furthermore, during heating, the hydraulic oil flow rate is adjusted according to the design requirements through the proportional valve. The hydraulic oil brings the waste heat of the hydraulic system and then evaporates the refrigerant for the second time in the second plate heat exchanger. The refrigerant that is not completely evaporated in the condenser absorbs the waste heat brought by the hydraulic oil in the second plate heat exchanger, and changes from liquid to gas, completing the phase change of the refrigerant. The waste heat is carried by the refrigerant and enters the compressor as latent heat, ensuring that the refrigerant is all gaseous before entering the compressor and then the next cycle is carried out. When the gaseous refrigerant condenses into liquid at the first plate heat exchanger, this part of the heat is released.

[0013] The entire heating and cooling air-conditioning system is controlled by a controller, which reads the antifreeze temperature in the antifreeze circulation system and the high and low pressures of the refrigerant circuit, controls the speed of the compressor, the speed of the condensing fan in the condenser, the on-off of the first stop valve and the second stop valve, the flow of the water pump, the opening of the electronic expansion valve, and communicates with the air-conditioning control panel to receive work instructions and feedback the system working status.

[0014] The present invention organically integrates the cooling and heating systems of the cab, and realizes the state switching of the first plate heat exchanger by controlling the state of the electronic expansion valve (fully open or adjusted according to the evaporation temperature of the condenser). In summer cooling, the electronic expansion valve is fully open, and the first plate heat exchanger is the refrigerant channel; the water pump, the cab water air conditioning core, the second plate heat exchanger, the second stop valve, are connected to form a second antifreeze circulation loop to provide cooling needs for the cab. In winter heating, the electronic expansion valve adjusts the opening according to the evaporation temperature of the condenser (the condenser is used as an evaporator at this time), and the first plate heat exchanger is the condenser at this time; the water pump, the cab water air conditioning core, the first plate heat exchanger, the first stop valve, are connected to form a first antifreeze circulation loop to provide heating needs for the driver. The above structure replaces the original cab air conditioning system. The overall structure is ingenious, which greatly simplifies the structure, reduces costs, saves layout space, and simplifies the overall vehicle layout. The switching of cooling and heating needs can be achieved by controlling the working status of the stop valve and the electronic expansion valve. The control is simple, and the cooling and heating effects are good, which makes up for the defects of the current two solutions.

[0015] In addition, the second plate heat exchanger of the present invention adopts three branches and three media to form a waste heat recovery hydraulic oil circulation loop with the proportional valve and the hydraulic system. The vehicle hydraulic system will generate a certain amount of waste heat during the operation of the vehicle. Therefore, when the air conditioning system is heating in winter, the hydraulic system can provide heat for the evaporation of the refrigerant. That is, in the low temperature environment in winter, the existing problem of low energy efficiency ratio of heat absorption from the environment or inability to absorb heat is solved, and the waste heat of the vehicle is effectively recycled, which improves the comfort of the cab heating in winter, reduces the electric energy consumed by heating demand, and increases the vehicle's cruising range. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention;

[0017] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0018] Figure 3 It is a schematic diagram of the arrangement of three medium layers of the second plate heat exchanger of the present invention.

[0019] Numbers in the figure: 1-compressor; 2-first plate heat exchanger; 3-electronic expansion valve; 4-condenser; 5-thermal expansion valve; 6-second plate heat exchanger; 7-first stop valve; 8-second stop valve; 9-water pump; 10-cab water air conditioning core; 11-proportional valve; 12-hydraulic system. DETAILED DESCRIPTION

[0020] The present invention is further explained below in conjunction with the examples. The following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0021] Example 1

[0022] like Figure 1 As shown, the pure electric engineering machinery cooling and heating air conditioning system includes a compressor 1, a first plate heat exchanger 2, an electronic expansion valve 3, a condenser 4, a thermal expansion valve 5, and a second plate heat exchanger 6 connected in sequence to form a refrigerant circulation loop, that is, the refrigerant starts from the compressor 1, passes through the first plate heat exchanger 2, the electronic expansion valve 3, the condenser 4, the thermal expansion valve 5, and the second plate heat exchanger 6 in sequence, and then returns to the compressor 1. The system also includes a cab water air conditioning core 10, the liquid outlet of the cab water air conditioning core 10 is connected to the liquid inlet of the first plate heat exchanger 2 and the second plate heat exchanger 6 respectively, and the liquid inlet of the cab water air conditioning core 10 is connected to a water pump 9, and the water pump 9 is connected to the liquid outlet of the first plate heat exchanger 2 through the first stop valve 7 and the liquid outlet of the second plate heat exchanger 6 through the second stop valve 8.

[0023] The first plate heat exchanger 2 and the second plate heat exchanger 6 are both provided with an antifreeze layer and a refrigerant layer, that is, two inlets and two outlets are adopted, and the two medium layers are arranged alternately.

[0024] The cooling and heating control of this system is as follows:

[0025] Refrigeration control: The controller controls the electronic expansion valve 3 to be fully open, and the thermal expansion valve 5 adjusts the opening according to the evaporation temperature of the refrigerant in the second plate heat exchanger 6. At this time, the first plate heat exchanger 2 is only a channel. The high-temperature and high-pressure gaseous refrigerant compressed by the compressor 1 passes through the first plate heat exchanger 2 and the electronic expansion valve 3 in turn to reach the condenser 4, condenses through the condenser 4, and then passes through the thermal expansion valve 5 to reach the second plate heat exchanger 6 for evaporation, and then returns to the compressor 1 to form a refrigerant cycle; at the same time, the controller controls the first stop valve 7 to be closed and the second stop valve 8 to be opened, and the antifreeze liquid circulates to the second plate heat exchanger 6 to be cooled after heat exchange with the refrigerant, and then circulates to the cab water air conditioning core 10 through the second stop valve 8 and the water pump 9 in turn to cool the cab;

[0026] Heating control: The controller controls the opening of the electronic expansion valve 3 according to the evaporation temperature of the refrigerant in the condenser 4, and the thermal expansion valve 5 adjusts the opening according to the evaporation temperature of the refrigerant in the second plate heat exchanger 6. The high-temperature and high-pressure gaseous refrigerant compressed by the compressor 1 is condensed in the first plate heat exchanger 2 and then reaches the condenser 4 through the electronic expansion valve 3. At this time, the condenser 4 acts as an evaporator to evaporate the refrigerant once and then reaches the second plate heat exchanger 6 through the thermal expansion valve 5. The second plate heat exchanger 6 evaporates the refrigerant for the second time and then returns to the compressor 1 to form a refrigerant cycle; at the same time, the controller controls the first stop valve 7 to open and the second stop valve 8 to close, and the antifreeze liquid circulates to the first plate heat exchanger 2 to absorb heat and heat up. The heated antifreeze liquid then circulates to the cab water air conditioning core 10 through the first stop valve 7 and the water pump 9 in turn to heat the cab.

[0027] Example 2

[0028] On the basis of Example 1, Figure 2 As shown, the second plate heat exchanger 6 is also connected to the hydraulic system 12 and the proportional valve 11 of the vehicle in sequence to form a loop. The second plate heat exchanger 6 uses three branches and three media, such as Figure 3 As shown, it includes an antifreeze layer, a refrigerant layer and a hydraulic oil layer in sequence. The second plate heat exchanger 6, the proportional valve 11 and the hydraulic system 12 form a hydraulic oil circulation loop for waste heat recovery. The hydraulic system 12 carries waste heat generated by the operation of the vehicle. The circuit can realize the recovery of waste heat of hydraulic oil, the secondary evaporation of refrigerant, and the refrigeration of the water air conditioning circulation loop in the cab respectively through the control of valve components.

[0029] During the heating process, the refrigerant exchanges heat with the antifreeze at the first plate heat exchanger 2 to cool down and condense. The electronic expansion valve 3 adjusts the opening according to the evaporation temperature of the refrigerant in the condenser 4. The refrigerant absorbs the ambient temperature in the condenser 4 and evaporates once. At this time, the condenser becomes the evaporator in the refrigerant cycle. In winter, the ambient temperature is low and the evaporation is incomplete. The thermal expansion valve 5 adjusts the opening according to the evaporation temperature of the refrigerant in the second plate heat exchanger 6. The proportional valve 11 adjusts the flow of hydraulic oil according to the design requirements. After the hydraulic oil absorbs the waste heat of the hydraulic system, it evaporates the refrigerant twice in the second plate heat exchanger 6, so that the refrigerant is guaranteed to return to the compressor 1 in a gaseous state.

[0030] The remaining parts not mentioned are the same as those in Example 1 and will not be described in detail.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the principle of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A pure electric engineering machinery cooling and heating air conditioning system, characterized in that: The system includes a compressor, a first plate heat exchanger, an electronic expansion valve, a condenser, a thermal expansion valve and a second plate heat exchanger which are sequentially connected to form a refrigerant circulation loop; the system also includes a cab water air conditioning core, the liquid outlet of the cab water air conditioning core is respectively connected to the first plate heat exchanger and the liquid inlet of the second plate heat exchanger, the liquid inlet of the cab water air conditioning core is connected to a water pump, the water pump is respectively connected to the liquid outlet of the first plate heat exchanger through a first stop valve, and is connected to the liquid outlet of the second plate heat exchanger through a second stop valve, The first plate heat exchanger and the second plate heat exchanger both include an antifreeze layer and a refrigerant layer. The second plate heat exchanger is also connected to the hydraulic system and the proportional valve in sequence to form a loop.

2. The pure electric engineering machinery cooling and heating air conditioning system according to claim 1, characterized in that: The second plate heat exchanger comprises an antifreeze liquid layer, a refrigerant layer and a hydraulic oil layer in sequence.

3. A control method for a cooling and heating air conditioning system of a pure electric engineering machinery according to any one of claims 1 to 2, characterized in that: The control method includes cooling control and heating control. Refrigeration control: The controller controls the electronic expansion valve to be fully open, and the thermal expansion valve adjusts the opening according to the evaporation temperature of the refrigerant in the second plate heat exchanger. At this time, the first plate heat exchanger is a channel, and the high-temperature and high-pressure gaseous refrigerant compressed by the compressor passes through the first plate heat exchanger and the electronic expansion valve in turn to reach the condenser, condenses through the condenser, and then passes through the thermal expansion valve to reach the second plate heat exchanger to absorb heat and evaporate, and then returns to the compressor to form a refrigerant cycle; at the same time, the controller controls the first stop valve to be closed and the second stop valve to be opened, and the antifreeze liquid that has absorbed the heat from the cab environment and heated up circulates to the second plate heat exchanger to exchange heat with the refrigerant to be cooled and cooled, and then circulates to the cab water air conditioning core through the second stop valve and the water pump to cool the cab; Heating control: The controller controls the opening of the electronic expansion valve according to the evaporation temperature of the refrigerant in the condenser, and the thermal expansion valve adjusts the opening according to the evaporation temperature of the refrigerant in the second plate heat exchanger. The high-temperature and high-pressure gaseous refrigerant compressed by the compressor is condensed in the first plate heat exchanger and then reaches the condenser through the electronic expansion valve. At this time, the condenser acts as an evaporator to evaporate the refrigerant once and then reaches the second plate heat exchanger through the thermal expansion valve. The second plate heat exchanger evaporates the refrigerant for the second time and then returns to the compressor to form a refrigerant cycle; at the same time, the controller controls the first stop valve to open and the second stop valve to close, and the antifreeze in the cab that has been cooled by heat release circulates to the first plate heat exchanger to absorb heat and heat up. The heated antifreeze then circulates to the cab water air conditioning core through the first stop valve and the water pump to heat the cab.

4. The control method of the cooling and heating air conditioning system of pure electric engineering machinery according to claim 3 is characterized by: During heating, the flow of hydraulic oil is adjusted by a proportional valve. The hydraulic oil brings the waste heat of the hydraulic system and evaporates the refrigerant again in the second plate heat exchanger.

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